A COURSE OF LECTURES DELIVERED BEFORE A JUVENILE
AUDIENCE AT THE ROYAL INSTITUTION

BY

MICHAEL FARADAY, D.C.L., F.R.S.

EDITED BY

WILLIAM CROOKES, F.C.S.

A NEW IMPRESSION, WITH ILLUSTRATIONS

LONDON

CHATTO & WINDUS

1908

PREFACE

From the primitive pine-torch to the paraffin candle, how wide an
interval! between them how vast a contrast! The means adopted by man to
illuminate his home at night, stamp at once his position in the scale of
civilisation. The fluid bitumen of the far East, blazing in rude vessels
of baked earth; the Etruscan lamp, exquisite in form, yet ill adapted to
its office; the whale, seal, or bear fat, filling the hut of the Esquimaux
or Lap with odour rather than light; the huge wax candle on the glittering
altar, the range of gas lamps in our streets,--all have their stories to
tell. All, if they could speak (and, after their own manner, they can),
might warm our hearts in telling, how they have ministered to man's
comfort, love of home, toil, and devotion.

Surely, among the millions of fire-worshippers and fire-users who have
passed away in earlier ages, _some_ have pondered over the mystery of
fire; perhaps some clear minds have guessed shrewdly near the truth. Think
of the time man has lived in hopeless ignorance: think that only during a
period which might be spanned by the life of one man, has the truth been
known.

Atom by atom, link by link, has the reasoning chain been forged. Some
links, too quickly and too slightly made, have given way, and been
replaced by better work; but now the great phenomena are known--the
outline is correctly and firmly drawn--cunning artists are filling in the
rest, and the child who masters these Lectures knows more of fire than
Aristotle did.

The candle itself is now made to light up the dark places of nature; the
blowpipe and the prism are adding to our knowledge of the earth's crust;
but the torch must come first.

Among the readers of this book some few may devote themselves to
increasing the stores of knowledge: the Lamp of Science _must_ burn.
"_Alere flammam._"

W. CROOKES.

CONTENTS.

LECTURE I.

A CANDLE: THE FLAME--ITS SOURCES--STRUCTURE--MOBILITY--BRIGHTNESS

LECTURE II.

BRIGHTNESS OF THE FLAME--AIR NECESSARY FOR COMBUSTION--PRODUCTION OF WATER

LECTURE III.

PRODUCTS: WATER FROM THE COMBUSTION--NATURE OF WATER--A COMPOUND--HYDROGEN

LECTURE IV.

HYDROGEN IN THE CANDLE--BURNS INTO WATER--THE OTHER PART OF WATER--OXYGEN

LECTURE V.

OXYGEN PRESENT IN THE AIR--NATURE OF THE ATMOSPHERE--ITS PROPERTIES--OTHER
PRODUCTS FROM THE CANDLE--CARBONIC ACID--ITS PROPERTIES

LECTURE VI.

CARBON OR CHARCOAL--COAL GAS--RESPIRATION AND ITS ANALOGY TO THE BURNING
OP A CANDLE--CONCLUSION

LECTURE ON PLATINUM.

NOTES.

THE CHEMICAL HISTORY OF A CANDLE

LECTURE I.

A CANDLE: THE FLAME--ITS SOURCES--STRUCTURE--MOBILITY--BRIGHTNESS.

I purpose, in return for the honour you do us by coming to see what are
our proceedings here, to bring before you, in the course of these
lectures, the Chemical History of a Candle. I have taken this subject on a
former occasion; and were it left to my own will, I should prefer to
repeat it almost every year--so abundant is the interest that attaches
itself to the subject, so wonderful are the varieties of outlet which it
offers into the various departments of philosophy. There is not a law
under which any part of this universe is governed which does not come into
play, and is touched upon in these